Articles and News

The Invisible Infrastructure: What’s Really Inside Your Manhole?

• LADTECH INC.
• January 05, 2026

The Invisible Infrastructure: What’s Really Inside Your Manhole?

For most residents, a manhole is nothing more than an iron lid in the middle of the street. But for municipal leaders and public works departments, it is a critical gateway to a massive, complex network of pipes and processing centers. Understanding what lies beneath that lid—and specifically how the uppermost section of the manhole functions—is the difference between a high-performing utility and a budgetary nightmare.

The Anatomy of a Manhole

A standard manhole is composed of several key components:

• The Lid: The heavy iron surface interface.
• The Chimney (Adjustment) Section: The topmost portion that bridges the gap between the main manhole structure and the street surface.
• The Cone and Barrel: The main vertical structural sections.
• The Bench and Invert: The bottom floor and the channel that guides wastewater.

While the deep concrete barrel is designed to last for decades, the chimney section is notoriously the weakest link in the entire system. Because it sits just inches below the pavement, it bears the brunt of heavy traffic loads, ground shifting, and—most destructively—the relentless freeze-thaw cycles of the changing seasons.

The Hidden Threat: Inflow and Infiltration (I&I)

When a manhole chimney section deteriorates or is improperly installed, it creates a pathway for Inflow and Infiltration (I&I).

• Inflow occurs when surface stormwater pours directly into the sewer through cracks or gaps.
• Infiltration happens when groundwater seeps into the system through faulty joints and porous, weathered concrete.

Why does this matter? Every gallon of “clean” water that enters the sanitary sewer must be transported and treated at the wastewater plant as if it were sewage. This doesn’t just waste energy; it robs your treatment plant of its capacity. Industry studies show that I&I can account for up to 45% of a treatment plant’s annual flow, leading to premature plant expansions and potential regulatory fines that can reach six figures.

The True Cost of a “Minor” Leak

It is easy to overlook a single faulty manhole, but the math tells a different story. A single 24-inch manhole with just one inch of standing water over a leaky chimney can allow over 1,000 gallons of inflow per hour.

In a single heavy rain event lasting 24 hours, that one manhole adds 24,000 gallons of unnecessary water to your system. At an average treatment cost of $2.00 to $5.00 per 1,000 gallons, just two or three deteriorated manholes can cost a municipality thousands of dollars in annual treatment fees—not to mention the labor costs for emergency repairs when the surrounding soil erodes, creating dangerous sinkholes and street failures.

The Superior Solution: Ladtech’s HDPE Adjusting Rings

Traditional repairs involve “stacking” concrete rings using mortar and shims. This “BAND-AID” approach is destined for failure because concrete is porous and mortar eventually cracks under traffic vibration.

Ladtech’s HDPE (High-Density Polyethylene) Adjusting Rings offer a permanent, superior alternative. Here is why forward-thinking municipalities are making the switch:

• 100-Year Life Expectancy: Unlike concrete, which may last only 5 to 25 years in harsh environments, Ladtech’s HDPE is impervious to hydrogen sulfide gas (H2S), road salts, and chemical corrosion.
• Watertight Protection: Used with a butyl rubber sealant, Ladtech rings create a mortarless, completely watertight seal that eliminates I&I at the source.
• Unmatched Efficiency: A concrete ring can weigh 100 lbs and require hours of labor and “curing” time. A Ladtech ring weighs only 6 lbs, allows for precision adjustments as thin as ¼-inch, and can be installed in 20 to 30 minutes.
• Road-Ready Durability: Rated for HS-25 traffic loads, these rings are engineered to withstand the heaviest pounding from municipal traffic without cracking or breaking.

Conclusion: Investing in the Future

Maintaining a municipal sewer system is a game of marginal gains. By replacing failing concrete chimney sections with Ladtech HDPE Adjusting Rings, cities can drastically reduce labor hours, eliminate treatment costs for “ghost water,” and extend the life of their infrastructure.

It is time to stop the cycle of temporary fixes. For your next resurfacing or repair project, choose the product that protects your budget as well as it protects your pipes.

Resources & Further Reading:

• Ladtech, Inc. – HDPE vs. Concrete: A Comparison of Manhole Ring Materials. ladtech.com
• Envirosight – Inflow and Infiltration (I&I): Causes and Costs. envirosight.com
• The Man Pan – The Real Cost of Surface Inflow. themanpan.com
• EPA – Collection Systems O&M: Fact Sheet on Infiltration and Inflow Control. epa.gov

Written By - Dwight Wiedrich

Dwight Wiedrich is the founder of LadTech, an innovative, DOT-approved, patented HDPE manhole ring manufacturer. He has solved problems in the underground space for over 40 years.